In the past 12 months, we have produced 11 mutant IL-2 proteins by site-- directed mutagenesis and these mutant proteins have provided useful information as to the functional structure of IL-2. However, none of these mutant proteins can serve as a good agonist or antagonist. We are attempting to reach this goal by engineering IL-2 to fuse with another molecule to generate a multiple function molecule or to generate a more effective molecule. We have constructed an IL-2 mutant protein which has RGDS sequence added to the N terminal of IL-2. The purified mutant protein has both adhesive activity and proliferative activity. On the other hand, mutant protein with RGES added to the N terminal of IL-2 has only proliferative activity but not adhesive activity.